I've been using the Izotope denoiser in Sonar and it was working fine.  However, it's suddenly started causing lots of cracks and pops, rendering the once useful program basically unusable.  I was wondering if anyone else has had a similar problem?  What do you think the issue is: the software (Izotope Rx4), my computer (Windows/8gb ram intel i.7, 2.6ghz), my audio interface (focusrite forte), or something else?  Any advice?  
 
Thanks for the help!
 
Additional info:  When I add the denoiser to a track it adds clicks and pops everywhere in my entire project...

A specific project? How about a new project?
 
For starters...
Run windows update everywhere.
Update plugins to latest versions.
Update your audio interface firmware and drivers.
If you are running ASIO4ALL remove.
 
Ta.

Check your latency, you may need to increase it.

Lynn
Check your latency, you may need to increase it.

That would be my guess as well. Restoration software likes CPU power.

Yup I agree, but I recommended getting your maintenance up to date before you do this.

I boosted the latency on my Forte from 2ms to 6ms and everything now seems fine.  Thanks for helping!